(i) Field of the Invention
This invention relates to a novel pumping system.
(ii) Description of the Prior Art
For many pumping uses there is a requirement to have a "two pump" system. One of the pumps provides high pressure at low fluid flows, while the second pump provides a high flow rate with low fluid head requirements. The common practice heretofore has been to utilize individual pumps or to use, as the second pump, magnetically coupled pumps which would not leak.
A severe problem exists in pumping and/or metering fluids at high pressures where leakage of one or both of the fluids can cause damage to the environment or a loss of valuable material. Among other limitations to the present pumping system are the fact that two motors are required and that the second pump usually has leakage problems at the shaft. Furthermore, the frictional losses at the seal vary directly with the pressure. Moreover, in this system, each pump requires a motor and a means of sealing the fluid from the motor. In magnetically coupled pumps: (a) only very clean liquids may be pumped; (b) only low heads can be accomplished; and (c) as the volume to be pumped increases, the pump size and operating pressure decrease. At any rate, if one of the pumps or motors fails, the process can be disrupted causing possibly large losses of material or equipment.
Another common practice utilizes one pump to provide high pressure and flow requires high hose pressure. A disadvantage of such practice is that the fluid is continuously pressurized and then depressurized at a pressure regulator and consequently that energy is lost in pressurizing and depressurizing.
Many patents purport to provide improvements in flow regulating or mixed flow pumps.
Canadian Pat. No. 565,930 issued Nov. 11, 1958 to Karl Wernert, Mulheml-Ruhr, Germany, provides a variable output rotary pump structure, including a centrifugal pump, an adjacent rotary pump and a common driving shaft. The structure is such that when the centrifugal pump reaches a set pressure, it automatically cuts out the rotary pump.
Canadian Pat. No. 569,285 issued Jan. 20, 1959 to Strausak & Cie., Lohn, Switzerland, provides a flow-regulatory pumping device for fuel supply. In the patent, two pumps (a first fixed delivery and a second variable delivery) are driven from a common shaft and are connected in series relative to fuel flow. Structure is provided to control and measure the amount of fuel delivered by each pump.
Canadian Pat. No. 574,816 issued Apr. 28, 1959 to Thompson Products, Inc., Cleveland, U.S.A., provides a mixed flow multiple pump. The invention includes the combination of a main positive displacement pump and an auxiliary, low-inlet-loss, centrifugal pump placed in series ahead of the main positive displacement pump.
Canadian Pat. No. 588,457 issued Dec. 8, 1959 to Borg Warner Corp., Chicago, Ill., U.S.A., provides a staging-type altitude fuel pump. It provides a high capacity first stage to supply a necessary high volume of fuel at a high pressure, and a second stage pump which operates at low inlet pressures and high vapor-liquid ratios. The inventive combination uses two pumps for the first stage, one pump to provide the second pump with the necessary volume of fluid at high pressure, and an auxiliary pump to assist the main pump during periods of adverse conditions.
Canadian Pat. No. 623,140 issued July 4, 1961 to United Shoe Machinery Company of Canada, Limited, Montreal, Quebec, provides a pump for use in blood circulation. A pair of compressible tube rotary impeller-type pumps are connected in such a way to the human body that one pump is connected to venous blood and the other pump is connected to arterial blood. Both pumps are operated by the same shaft.
Canadian Pat. No. 634,944 issued Jan. 23, 1962 to Sven A. Noren, Stockholm, Sweden, provides a combined pump device. The patent includes a viscosity-type pump operatively and directly connected to the inlet of a displacement-type pump so that it operates with a velocity proportional to the velocity of the displacement pump. This provides a greater pressure at the inlet side of the displacement-type pump.
Canadian Pat. No. 664,418 issued June 4, 1963 to Gilbert R. Funk and Robert E. Holtgrieve, Waukesha, Wis., U.S.A., provides a metering pump. In the patent, a primary pump to supply the high pressure and a secondary pump with pressures balanced across it are provided in which the rotors of the pump are mounted on the same shaft. The inventive contribution involves connecting a meter with the common shafting. The amount delivered by the series-connected pumps will be the amount displaced by the metering pump.
Canadian Pat. No. 679,875 issued Feb. 11, 1964 to The Weatherhead Company, Cleveland, Ohio, U.S.A., provides a pump cooling apparatus. In the inventive concept, a variable displacement pump is coupled with a secondary or centrifugal pump so that there is a flow of fluid through the pump and between the pump and a reservoir as a result of a pressure differential created by the secondary or centrifugal pump. The secondary pump is connected to the reservoir.
Canadian Pat. No. 713,837 issued July 20, 1965 to Danfoss ved ing. M. Clausen, Nordborg, Denmark, provides a two stage gear pump, namely, a suction stage pump and a pressure stage pump. The invention provides an axial sealing surface for the suction pump, the sealing surface being in the form of an oil relief valve.
Canadian Pat. No. 781,753 issued Apr. 2, 1968 to George R. Sosemn et al., Burbank, Calif., U.S.A. provides a plural output pump. The single pumping device can pump two or more fluids at the same or different output pressures and at the same or different volumetric ratios. It includes a fixed displacement primary pump and a variable displacement secondary pump. There is an interrelated pumping mechanism between the first and second pumps.
Canadian Pat. No. 783,942 issued Apr. 30, 1968 to Drysdale & Company Limited, Glasgow, Scotland, provides a fluid supply apparatus. According to the invention, the inlet of a centrifugal pump is connected to a source of fluid and its outlet is connected to the inlet of a positive displacement pump which is connected to the fluid system.
Canadian Pat. No. 809,422 issued Apr. 1, 1969 to Siemen & Hinsch mbH, Itzehoe/Holstein, Germany, provides a reversible rotary pump. According to the invention, the reversible rotary pump is provided with a side channel shape designed for optimum operation in one direction of fluid flow. A second side channel stage is designed for optimum operation in the opposite direction of fluid flow. The two side channel stages are connected to operate in series. The pump is also provided with reversible drive means.
Canadian Pat. No. 855,975 issued Nov. 17, 1970 to Von Roll AG., Gerlatingen, Switzerland, provides a multiple unit hydraulic pump. The independent pumping mechanisms are disposed within a common housing. This can allow the housing to include a built-in reservoir.
Canadian Pat. No. 1,081,539 issued July 15, 1980 to W. F. Krueger, is directed to pumping apparatus for pumping metered quantities of material from one location to another. The pumping means includes a pair of pump cylinders. Ball check valves and back pressure interconnection means are also provided.
By U.S. Pat. No. 4,054,544 issued Oct. B 18, 1977 to H. Penhexter, apparatus is provided for exposing a fluid to a negative pressure.
Basically according to this patent, an apparatus is provided for subjecting a fluid to a negative pressure. The apparatus includes a receptacle with a partition reciprocable therein and dividing the cylinder into two chambers. The partition is arranged to sweep a lesser volume in one of those chambers than is swept in the other chamber. A fluid is admitted to the smaller volume chamber as that chamber expands and is delivered from the smaller volume chamber to the larger volume chamber as the larger chamber expands. As the partition reverses and moves to expand the smaller volume chamber, fluid is moved out of the larger volume chamber to a separating means.
U.S. Pat. No. 4,070,280 issued Jan. 24, 1980 to Desalination Systems Inc., provides apparatus for purifying water by reverse osmosis operable by a handle or pedal. The reverse osmosis apparatus of this patent includes a pump for pressurizing feed water introduced into a pressure resistant container in which is slidably mounted a semi-permeable membrane cartridge. A rod, attached to an end of the semi-permeable membrane cartridge, passes slidably and sealingly through one end of the pressure resistant container and is connected to means for reciprocal actuation. Means, preferably common, are provided to actuate the pump and the rod which imparts longitudinal reciprocal motion to the rod and the membrane cartridge within the pressure resistant container, thereby providing improved turbulence and circulation of the feed water through the semi-permeable membrane cartridge over the membrane surfaces. The common means may be in the form of a lever operated by a handle or pedal, or by a power source such as an electric motor.
U.S. Pat. No. 4,096,052 issued June 20, 1978 to H. Pinkerton provides apparatus for and a method of accurately proportioning and mixing fluids. The patentee in U.S. Pat. No. 4,096,052 provides apparatus for accurately proportioning and mixing fluids comprising a double acting piston/cylinder unit of which the cylinder is divided into two chambers by the piston and the volume of the cylinder swept by the piston at one end of the piston is lesser than that at the other end. An inlet connection for a first fluid is made to one chamber, a conduit connects the two chambers and includes a connection to a source of the second fluid. Valve means are associated with the conduits and are effective to cause a charge of first fluid to be delivered to one chamber and thereafter to be transferred to the other chamber drawing fluid from the source of a second fluid to make up for the difference in the volumes of the chambers. The valve means then cooperate to cause the mixed fluids to be discharged from the other chamber as the one chamber is again charged with the first fluid.
U.S. Pat. No. 4,172,033 issued Oct. 23, 1979 to DWS Inc., relates to an artificial kidney system which includes first apportioning means for providing at least a substantial part of the dialysate solution for a dialyzer, and second apportioning for receiving dialysate solution from the dialyzer. Means coordinate the operation of the second apportioning means with the first apportioning means for predetermining the ratio of dialysate solution passing in and out of the dialyzer. A negative pressure means and a pressure reducer are disposed in that order between the dialyzer and the second pump for providing a predetermined constant pressure to the input of the second pump while sufficient negative pressure is applied to the dialyzer for supplying just the quantity of dialysate solution demanded by the second pump. The negative pressure means suitably comprises a pumping device and a bypass connected thereacross. According to the ratio of pumping rates selected for the first and second pumps, the amount of fluid withdrawn or even added can be accurately predetermined.
U.S. Pat. No. 4,178,240 issued Dec. 11, 1979 to H. Pinkerton provides a system for handling two liquid streams comprising an hydraulic circuit including a pair of receptacles each provided with movable partition means dividing it into first and second chambers. Rod means extending through a first chamber of each receptacle connects the partition means and is effective to cause reciprocation of one partition means to be repeated by the other so that as the first chamber of one receptacle is expanded, the first chamber of the other receptacle is contracted. A quantity of the first liquid is delivered alternately to the first and second chambers of the receptacle as those chambers expand. As those chambers contract first liquid is passed through conduit means from the first and second chambers of the one receptacle to the first and second chambers, respectively, of the other receptacle. A source of second liquid is connected to the conduit means and liquid removal means is connected to the conduit to remove liquid from the circuit in quantities equal to the quantity of second liquid admitted to the circuit.
U.S. Pat. No. 4,197,196 issued Apr. 8, 1980 to H. Pinkerton provides an improvement in the hemodialysis system of his U.S. Pat. No. 4,096,052, including a dialyzer having a semi-permeable membrane, apparatus for accurately proportioning and mixing fluids comprising a double acting piston/cylinder unit of which the cylinder is divided into two chambers by the piston and the volume of the cylinder swept by the piston at one end of the piston is lesser than at the the other end.